1. Field of the Invention
The invention is directed to one-leaf or two-leaf sliding doors, swinging doors or pocket doors with an electric, pneumatic or hydraulic drive, in particular for vehicles, wherein a spindle is provided, the leaf or leaves being connected therewith via a nut, wherein, in the case of two-leaf doors, the spindle is constructed symmetrically with respect to the center of the door, and wherein the door drive acts either rotatively on the spindle or linearly on one of the leaves.
2. Description of the Related Art
A swinging/sliding door with an electric drive is known, for example, from DE-C 36 30 229 which discloses a two-leaf door in which each leaf has an upper and a lower guide rail in which at least one roller engages in each instance. The vertically extending rotational axis of the rollers is swivelable about a vertically extending door post pipe, this swiveling movement causing the door to open outward.
Since the electric drive can carry current only when the door is actuated, a dead-center mechanism is required for locking the door so as to ensure that the closed door cannot be opened by manipulation.
As another consequence of this dead-center mechanism, the door is only locked when it has been moved completely into the final closing position, so that any failure of the drive or any obstacle preventing the door from being closed completely will allow the door to open, e.g., as a result of the vibrations of the moving vehicle. On the other hand, the dead-center mechanism must also be adjusted precisely which, under heavy-duty operating conditions and during large differences in temperature, is difficult and accordingly disadvantageous.
The use of the door post pipe which is associated with each door leaf and is located at the edge of the door opening in the region of the lateral closing edge is another great disadvantage. When the door is open, this door post pipe can be covered only with difficulty and, even then, not completely. In the process of closing the door, the door post pipe in the region of the lateral closing edge poses the most serious kind of risk, especially for children and older, frail persons seeking a handhold.
Problems also occur in alignment because the door post pipe must be fitted and aligned in the floor region as well as in the roof region. There is no need to demonstrate in particular such problems which occur in all three axial directions.
Swinging/sliding doors with a pneumatic or hydraulic drive in which the door leaves are guided in a swivelable manner by means of a slide so as to be longitudinally displaceable at a stationary circular supporting pipe have also been known from Austrian Patent document 188 323. The corresponding guide rails for the opening out movement and for longitudinal guidance are arranged on the vehicle side in the region of the upper edge and lower edge of the door. Suitable guide rollers are provided at the door leaf
The drive is effected via a cylinder-piston unit, and various lever mechanisms and scissor mechanisms have been suggested for reducing installation width. In the closed state, these doors are locked in the region of the lateral closing edge by a mechanism arranged in that location so that they remain closed while the vehicle is in motion in the event of a drop in pressure in the drive, but also because the normal operating pressure is not sufficient to prevent the door from opening in a reliable manner. It is not possible to achieve an operating pressure sufficient for this purpose in an economical manner due to the required wall thickness of the pipes and tubes.
The lock projecting beyond the free profile of the door at the height of the door handle in the region of the lateral closing edge poses a source of risk on a par with the door post pipe in the construction mentioned above.